1. Field of the Invention
The present invention relates to a method comprising: selecting a specific cell or cells to be analyzed from a specimen on a substrate; and isolating the cell or cells to be analyzed.
2. Description of the Related Art
At present, a research to analyze a function of a gene has been a matter of greatest concern. In the research of analysis of the gene function, cells are acquired from a specimen. A sample for the analysis of the gene function is directly sampled from the cells. Various types of an apparatus for sampling the cells or sample have been developed and used.
Various cell sampling methods for sampling the cells from a slice of a specimen will be described.
(1) A slice of a specimen is fixed onto a thin film plate. The slice of the specimen includes, for example, the cells to be sampled for the analysis of the functions of the gene. The thin film plate is irradiated with a laser beam of an ultraviolet wavelength region (UV laser beam) along a contour of the cells. Thereby, the cells to be sampled in the specimen are cut/separated together with the thin film plate.
Next, a cut/separated portion is irradiated with the UV laser beam out of focus with respect to the thin film plate. Thereby, the cut/separated portion in the specimen is flied. As a result, the cells to be sampled are acquired.
(2) A transparent cap for sampling to which a transfer film is attached is used. The transparent cap is laid on the specimen which has the cells to be sampled. The portion including the cells to be sampled in the specimen are irradiated with an IR laser beam through the transparent cap. Thereby, the cell portion to be sampled adheres to a transfer film surface.
(3) The specimen is attached onto the film. The surface to which the specimen is attached on the film is turned downwards. In this state, the UV laser beam is emitted along the contour of the cells from above. Thereby, the periphery of the cells to be sampled are cut off.
Next, the film is irradiated with the UV laser beam. Thereby, the cells to be sampled are detached from the film and dropped into a tray which is set below.
However, the method (1) comprises: cutting/separating the cells to be sampled together with the thin film plate; and subsequently irradiating the cut/separated portion with the UV laser beam out of focus to fly the portion. Therefore, a place of the cells to be sampled are not known. The cells are lost in many cases. Moreover, it is also expected that properties of the cells are changed by the UV laser beam.
Moreover, foreign particles such as dust are easily mixed in the sampled cells. It is necessary to fix the specimen onto the thin film plate beforehand. Therefore, the sampling operation of the cells requires troubles and is laborious.
The method (2) comprises: irradiating the cells to be sampled in the specimen with the IR laser beam transmitted through the transparent cap. Therefore, a spot diameter of the IR laser beam with which the cells to be sampled are irradiated cannot be reduced. The spot diameter of the IR laser beam is also sometimes larger than the size of the cells to be sampled. When the cells are irradiated with the laser beam having the spot diameter larger than the size of the cells to be sampled, together with the cells to be sampled, unnecessary surrounding cells also stick to the transfer film surface. For example, to sample a micro cell of five microns or less with a spot diameter of ten microns, the surrounding unnecessary cells also stick to the transfer film surface.
Since the cells to be sampled are attached to the transfer film surface, depending on a dry degree of the cells, the cells cannot well stick to the transfer film surface, and the cells cannot sometimes be sampled. It is impossible to sample the cells in a wet state. The sticking of the cells to the transfer film surface is influenced by conditions of the cells such as the dry degree of the cells. In other words, the capability of sampling the cells is limited by the conditions of the cells.
With an increase of the output of the IR laser beam with which the specimen is irradiated, an efficiency of attaching the cell portion to the transfer film surface to sample the cells is improved. On the other hand, when the output of the IR laser beam is increased, the cells burn.
The method (3) comprises: dropping the cell portion sampled by the irradiation with the UV laser beam down to the tray which is set below. Therefore, the place of the cells to be sampled is not known. Moreover, the foreign particles such as dust are easily mixed in the acquired cells. It is also expected that the properties of the cells are changed by the UV laser beam.
The above-described problems are summarized as follows.
(a) It takes much time to sample the cells to be sampled. Additionally, the cells are easily lost at a sampling time.
(b) It is difficult to acquire small cells. The cells which can be sampled are limited by a dry state of the specimen.
(c) It is impossible to acquire a large amount of cells having sufficient qualities in a short time by causes such as the change of the properties of the cells by the UV laser beam.